Posted in: Featured Article

Save Time and Money Making CNC Halloween Decorations

November 2014 Len Shelton Melissa Shelton

When my friend,Vern asked me if I'd write an article for Nuts & Volts demonstrating how to create a Halloween decoration tombstone on a CNC router, I was psyched. I’m always looking for new and interesting ways to show off all you can do with CNC machines. So, I agreed to give it a shot.



Create complex 3D contoured parts by combining fast and simple 2.5D pocketing and profiling operations with manual finishing techniques.

Getting Started

As with any project, you have to do your research. I needed to answer questions like: What do tombstones look like? How are they shaped? What do they say on them? How are people using them in their Halloween displays? Most importantly: How do I make them on a CNC router? So, I got a lot of great design ideas examining epitaphs and tombstones using Google image search. Unfortunately, most of the models I found required 3D contouring. With that type of work, I would first need to spend the time creating a 3D model and even more hours carving it out.

There are three primary phases to a CNC project:

1) Design: The drawing or CAD model.
2) Tooling: Creating the tool paths with CAM software.
3) Machining: Running the tool paths on the machine.

I am admittedly an impatient man. With time being a finite resource we can never get back, isn’t everyone looking for a faster way? So, let me show you how you can use CNC routers to shortcut the 3D contouring process. First and foremost, you want to create your basic shapes and features using 2.5D operations. This is by far the biggest time saver. I’m talking about pocketing, profiling, and drilling mainly flat features on flat parts. You then follow it up with a bit of hand sculpting. This marriage between CNC and hand work produces impressive results for this type of project, while shaving valuable time from the process.

Figure 1. Cutting 2" foam stock

To start, I needed an inexpensive material that I could get from my local home improvement store that was easy to work with. The obvious choice was 2” thick foam insulation which I purchased in a 4 x 8 foot sheet for about $28. It’s thick enough to allow for a lot of depth and contrast in my design, which really pops when hit by a spot light on my lawn display. I happened to pick up a panel of pink Owens Corning — the one with the Pink Panther mascot (Figure 1). Other brands in other colors should work equally well.

I Think I CAM, I Think I CAM ...

My favorite piece of CAM software is Vectric’s VCarve Pro. This is by far the easiest-to-use CAM software on the planet. I also like how their software shows you a 3D preview of what the finished part will look like (Figure 2). I mention the CAM software first because the feature I like best is the built-in drawing tools, as opposed to other applications that require third-party drawing tools. This allows you to blend the first and second phases with a single piece of software.

Figure 2. 3D view of the  tombstoned esign in VCarve Pro.

Given that, we will skip the first phase and blend it in to the second phase when we get to that point.

This article is not intended to be a step-by-step tutorial, so I will not go into the details of how to use VCarve Pro. There are plenty of excellent tutorials and sample projects on their website if you need help using any of their software. You can download the design files for this project at the article link or at to help get you started or if you want to simply recreate my design.

The first step in the CAM software is to define your stock (length, width, and height) and also where you want the origin (the zero location) to be. You can choose the back right corner at the bottom of the stock, top dead center, front left corner, or the top of the stock — it’s wherever you need it to be. It can depend on a lot of things, but typically people use the front left corner at the top of the stock.

The next step is to import your drawing from another drawing program. In this case, you can take advantage of Vcarve’s built-in drawing tools to create your shapes. I design machines and electronics for a living, so mechanical design comes naturally to me. However, I really struggle with organic design. So, whenever I come across a project like this, I rely on a variety of resources to help me.

Design, Fonts, and Clipart

There are plenty of sources of clipart available online, but many of them are click farms in disguise, so beware. I really like the CD-ROM/DVD clipart collections that include categorized catalogs (long live print!). Most of these designs require a lot of cleanup before they can be machined. They were not designed for CNC and will often have both disconnected and hidden vectors that have to be reworked first. Boolean drawing tools are your friend here.

Another great source of simple shapes are themed dingbat fonts. They require very little work to make them machinable. The horned head in my design was one of the “letters” in such a font. Speaking of fonts, there are tons of free font websites out there where you can find a multitude of themed type styles for your designs.

Once you are satisfied with your design, you will assign tool paths to the various shapes in it. Vcarve has a variety of tool path operations, but for this project we are only using the pocketing and profiling operations. With any of the tool path operations, you will be assigning the tool geometry, starting depth, depth of cut, step-over, feed rate, plunge rate, direction of cut, and so on. Because I was working with foam, I was able to take some overly aggressive cuts.

The order of operations is important when laying out your tool paths. For instance, you may need to cut your shallower pockets first when you have overlapping or embedded pockets. If the stock is being held from the outer edges, the last operation should be to do your final outside profile pass. I didn’t have an end mill long enough to make it through the whole slab of 2” foam, so on my outside profile, I cut it through as far as I could, then hand cut the rest of the way through with a knife. 

Now that you have your tool paths, you export them as g-code through the appropriate post-processor, and then carry that g-code over to the CNC machine on a USB thumb drive and load it into the control software. Our machines at Probotix run the open source software LinuxCNC.

Mount Up

I was cutting this particular part on the Probotix FireBall Comet™ CNC router that has a 25” x 25” work envelope (Figure 3). My foam slab was 18” x 24”, so I had to be careful that I mounted it to the table inside of the travel envelope of the machine. Double-sided 3M tape that has the green argyle backing is what I like to use for mounting stock to my table. Use a generous amount so the stock doesn’t come loose in the middle of the job.

Figure 3. Probotix Fireball Comet CNC Router. Figure 4. Screenshot of LinuxCNC showing tool paths.


Once the stock is mounted, install the tool into the spindle and then jog the tool over to the corner that you chose for the origin in the CAM software. Then, you will “touch off” each axis. What you are doing is telling the control software that you are now sitting at the starting point of each axis, or X0 Y0 Z0.

Give yourself a sanity check and look at the 3D toolpath on the display. You want to make sure that the tool path appears where you think it should within the work envelope bounding box on the screen (Figure 4). Then, hit the start button, sit back, and watch (Figure 5).

About 30 minutes later, you will have the basic tombstone carved out. So, pry it off the table and remove the double-sided tape. Figure 6 shows what it looked like after I cut off the outside scrap. Pretty cool already, but not very scary looking ... yet.

Figure 5. Fireball Comet in action - cutting the tombstone design. Figure 6. Tombstone after maching, but before handwork and paint.

The next step is to hand contour the piece to rough it up so it looks aged and weathered. There are many tools and methods you could use here, and you could spend a lot of time adding detail. Remember how impatient I am, though? I grabbed a die grinder with a rasp bit and a sanding wheel. I also used a hand rasp, and then smoothed out certain parts of the tombstone with some DAP fast drying latex caulk (Figure 7). Watch out for that die grinder — you can remove too much material in a hurry if you are not careful.

Figure 7. Die grinder, hand file, sand disc, and caulk.

Finishing Touches 

So far, so good, but have you ever seen a pink tombstone? Me neither. So, let’s change its color!

I love modern spray paint technology. There are many fast-drying exotic finishes available — your options are limitless. You can get a fantastic finish with little time and effort. A fleck stone spray paint finish was very tempting here, but since most spray paints will dissolve foam, I decided to use latex. I chose a satin gray as my base coat, and then used gray, black, and burnt umber mixes to weather and shade the tombstone (Figure 8).

Figure 8. Painting supplies and brushes.

Save Time, Save Money

You can spend a little time or a lot of time here. These tombstones are typically viewed under low light conditions, so I was looking mostly for contrast and depth, and that didn’t require a lot of time. Here is a breakdown of the time invested in this project:

• Research: 3 hours
• Design time: 1 hour
• CNC routing: 30 minutes
• Hand contouring: 10 minutes
• Painting: 30 minutes

So, my total time was 5:10.

Compare that to the 10-20 hours that could easily be spent on a full CNC 3D contouring to accomplish the same thing (Figure 9)!

Figure 9. Finished tombstone decoration.


All-in-all, I was pretty satisfied with the results from such a small investment in time. If I were going to do this again, I would have spent more time and creativity on the tombstone verbiage. 

Do a Google search for “funny epitaphs” to get some inspiration. Maybe include names of family members or friends. Add an Arduino and LED lights. Then, make a whole graveyard full of them if you want! 

Most importantly, make sure to work safe and have fun! NV







Probotix Comet CNC Router

Royalty Free and Public Domain bitmap and vector clipart libraries

Files for this project


Vectric Vcarve Pro

Free Fonts

Halloween Fonts

How to draw a creepy tombstone

Some definitions sourced from WikiPedia and other online resources

Posted on 10/14 at 2:41 pm
Posted in: Developing Perspectives

The Internet of Things

November 2014 Bryan Bergeron

Since the birth of the Internet, there has been talk of total connectivity — between people, people and their possessions, and things to things. Up until recently, the reality has been that such ecosystems existed only in academic and corporate research centers. Today, the Internet of Things (IoT) is a practical reality in many settings.

Let's start off with consumer goods. For the wellheeled, there's the Philips hue connected bulb ($60). It's a wireless bulb that screws into a regular light bulb socket. The difference is that you can control color and intensity via your iPhone or iPad from across the room or across the globe. If light bulbs aren't your thing (they don't do much for me), then another example of a commercially available IoT device is the Nest Protect smoke and carbon monoxide detector. No more surprises when you return from vacation to find all of your belongings smoldering from a house fire.

Then, there's the Parrot flower pot moisture sensor ($60) so that you know exactly when to water your roses, even when you're away from home. I haven't yet made the move to keyless locks. The Kwikset Kevo wireless deadbolt ($220) — while expensive enough to suggest it isn't a toy — leaves me a bit uncomfortable, knowing that a hacker could unlock my front door from his desk in some other country.

I'm partial to the web-enabled wireless cameras that can be accessed from anywhere. Check who's at the front door, keep an eye on the sitter, make sure the kids are doing their homework — the list is almost endless. Sure, this sort of snooping has been available for years, but never so "plug and play" with a smartphone.

On the non-commercial end of things, I've had the pleasure of working with some expensive gear that has yet to trickle down to the consumer market. My favorite is the pallet tracker. It's an RF unit that not only broadcasts the GPS location of the tagged pallet, but informs the receiver about handling and environmental conditions. 

For example, it can be set to sound an alarm if the internal accelerometer reads over 3 s, or, if the orientation of the tracker is shifted — as in flipped over. With such a device, it's possible to track a shipment across the globe, monitoring not only the location of the pallet but how it's been handled. (Be sure and check out the article this month by Ron Newton on a three-axis hockey puck accelerometer data logger that can be used for just such an application.)

I'm still waiting for a pair of running shoes that tell me not only how far and fast I've run — those have been available for years — but when it's time to buy a new pair of shoes based on impact sensors. It's the same with my toothbrush. I'm never certain exactly when to toss my brush for a new one. A connected brush that sends me an email after, say, 10,000 brushes would be helpful. I expect to see such a brush in my local CVS or Walgreens pharmacy within a year or two.

Best of all, I expect to see IoT kits that allow anyone to put anything on the Internet. Simply glue or nail it on whatever or whomever you want to track or control, and go about your business. One thing's for sure. With a mature IoT, I'll have to upgrade my data plan on my smartphone to avoid overuse charges. NV

Posted on 10/14 at 3:59 pm
Posted in: Nuts and Volts

New and in 3D: Automatic 3D data conversion and 3D-MID prototyping

October 2014

Aarbergen - At this year's Munich Electronica trade fair (November 11th-14th), Beta LAYOUT continues to announce interesting innovations. Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation.

3D-MID prototypes

Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. In mass production, these moldings are manufactured using injection molding techniques. For prototyping purposes, this method is not economically feasible. Coming soon, Beta LAYOUT will offer the ability to manufacture MID components in prototype and small batch quantities, including the production of formed components by 3D printing, metallic coating, laser patterning, selective metallization, and mounting.

This technology is economically viable for engineers and companies with prototype and low volume quantity requirements. Start of production is planned for the second quarter of 2015. For design of 3D-MID components, developers can download the free PCB - POOL® edition of layout software TARGET 3001! which will have extended design features.


With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation. In addition, a freely rotatable 3D view in PDF format is created which can be viewed using Adobe Reader. A link to order a laser sintered 3D model of the assembled PCB is provided, and a free 3D model is offered with PCB-POOL® prototype orders that can be used effectively for collision checking.

In addition, visitors to the Beta LAYOUT booth can receive information on the entire product range and services provided by Beta LAYOUT. These include PCB-POOL® - PCB prototype manufacture, PCB assembly, LASER STENCIL - SMD stencils, BETA – PROTOTYPES - 3D rapid prototyping, PANEL-POOL custom front plate manufacturing including color printing, and the BETA-eSTORE - tools and aids for prototype PCB assembly.

Posted on 10/14 at 9:41 am
Posted in: Nuts and Volts

WiDo - Open Source IoT Node (Arduino Compatible)

October 2014

The WiDo Open Source IoT Node Arduino Compatible is a WIFI IoT Node development board, which integrates WG1300 WIFI solution. The Wido's microcontroller is ATMEL ATmega32U4 and is maker friendly. Fully compatible with Arduino and periphery modules. This is a credit card sized controller that comes with everything you need to connect to the cloud. And it's under $30! 

  • Arduino compatible WIFI IoT Node development board
  • Integrates WG1300 WIFI chip
  • Support 2.4GHz IEEE 802.11 b/g network
  • On board 2.4G PCB Antenna


Get yours today at the

Posted on 10/14 at 9:14 am
Posted in: Nuts and Volts

Kickstarter: Dr.Duino

September 2014

Arduino has taken developers by storm, making developing your next widget easier than ever. But testing and debugging your next big thing is difficult and pains taking with Arduino. Stacked boards prevent access to the ones underneath it. Forcing you to stack and unstack your megalithic tower countless times each time bending pins out of shape, possibly breaking them. OUCH! What’s more, attaching probes for monitoring purposes is a pain, and what about a ground pin for my Oscilloscope, Digital Multi-meter (DMM) or Logic Analyzer?

Test Points, Test Points, Test Points!

Never struggle with where to grab a ground or monitor any signal from your Arduino to the shield above it again.

  • 4 large Gnd test points!!
  • 4 extra-large 5V &3 V test points.

Each test point is color coded for easy recognition.

  1. Green = Ground
  2. Red = 5 Volts
  3. Orange = 3.3Volts
  4. Black for Vref, Vin, and extra I/O!

RS-232 Baby!

Yep, built in RS-232 support out of box!

Communications Loop back testing supported by a simple jumper.

Built in Siren

Is your Arduino too far out of reach but need to know if an output is high or low? Well, assign your output pin to this little guy and BAM just listen for the siren! Better yet, this is connected directly to one of the PWM pins allowing you to control the volume.

Switch It UP

4 push button switches tied to input pins.

2 active high and 2 active low.

Light It UP

4 LED’s to help you debug your code.

Connected to the Arduino’s PWM pins allowing you to control brightness too!

POTs, POTs and more POTS

Six 10K large thumb wheel rotary Potentiometers pumped directly into the analog input pins.

Reset Switch

Reset your stack via the readily accessible reset switch.

How about some headers Please?

Every pin of the Arduino board has been brought out to a header. Allowing easy access for debugging purposes.

The window to your Boards Soul-

The middle of the Dr.Duino™has a hole! That’s right, simply plug your testy shield into any level of your stack. This allows you to still have access to all of your previous shields pins, IC’s, wires etc.

Pseudo Hardware

Were you struck in the middle of the night by your next invention but don’t have hardware on hand? Well, use the Dr.Duino™ kit and start writing your application code within mere milliseconds via commonly used hardware. Switches, POTS, LED’s, Sirens. Just plug in your Dr.Duino™ into your Arduino and start writing code!


Visit Dr. Duino Website to learn more! Or check out the Kickstarter to back the project! 

Posted on 09/14 at 2:57 pm
Posted in: Featured Article

The Ghost Phone

October 2014 Anthony Petrone

You walk into a darkened room where a rickety antique desk holds a dusty old telephone. To your surprise, it rings! You pick up the handset and hear static, hissing, and — just below the surface — the whispery words and scary sounds of a ghostly presence! You've just answered the Ghost Phone!

Figure 1A: Candlestick Style Phone

Since the days of old, many people believed the veil between the land of the living and the domain of the dead is at its thinnest on Samhain, All Hallows Eve, or — as we know it today — Halloween! Soothsayers, shaman, psychics, and mediums would all claim to provide patrons the privilege of speaking to their long-lost loved ones or would offer to carry back messages from the other realm — for a nominal fee, of course. So, how about we just skip the middleman and create a direct line to the afterlife? If this sounds like fun to you, then this fairly simple Halloween prop is just the ticket!

Propping It Up

I set out to create the Ghost Phone as a fun and interactive prop that anyone could make, using found objects and/or parts bought from local stores. Once the basic parts are gathered, it is unlikely that you'll spend more than a couple hours getting it all up and running since there's just a little wire splicing required. No tricky programming or custom-crafted printed circuit boards (PCBs) will be needed here. The premise is simple enough: When people get near the phone, it rings suddenly! Those brave enough to answer will be greeted with ghostly voices from the beyond.

There are three main components to this project; first of which is the phone itself. A suitable candidate can typically be found in a dusty corner of a thrift shop, in a box of junk at a garage sale, or maybe hidden in your very own attic. Second is the audio system which consists of a snap-action microswitch and a small MP3 player with a cheap set of headphones or earbuds. The third and final part is the ringer system. Though it may be possible to use the existing bells in the phone, I found it simpler to purchase an inexpensive low voltage electric bell and a "doorbell" style transformer to drive it. To control the ringer, I went to my local hardware store and purchased an off-the-shelf wireless light switching system that came with a handheld remote.

Though you can use pretty much any old corded phone for this project, I suggest you go for a style that fits the era of the haunted room in which you intend to use it. Victorian, Candlestick, WWII Army surplus, or even ‘50s era big black Bakelite style phones are all good candidates. Keep in mind that the modifications will likely render the phone unusable for "normal" phone service, so make sure you're not inadvertently destroying an expensive antique or family heirloom! For my haunt environment (classic Victorian haunt atmosphere), l found and purchased a replica Victorian-style phone.

Figure_1B: 50's Era Big Black Bakelite Style Phone Figure 2: Victorian Style Phone

Sounds ... Scary!

In operation, you want to give your guests the illusion that they are hearing voices from beyond the grave, but only when they pick up the receiver. To do this, I had to discover which wires went to the speaker in the earpiece of the phone handset. A quick search around Google and Wikipedia shows that many handsets used four wires: two for the microphone and two for the earpiece speaker.

Figure 3: Microphone to Speaker Wiring Schematic

We will need to access the two wires that go to the speaker in the handset. Lucky for us, older model telephones were long-lived devices and are typically easy to open for repairs. As such, it's normally a simple matter to unscrew the cover from the phone base and reveal the internal terminals and wiring. Once you have the cover removed, look carefully for the wires that come from the handset.

If you're lucky, they may be coded with the standard black/red/green/yellow colors. If this is so, you can try using the battery "tap test" to see if you can quickly identify the speaker. To do this, hold the green wire on the bottom terminal of the AA battery, then "tap" the red wire on the top terminal. At each tap, you should hear a pop and/or a slight crackle sound come from the speaker. If this doesn't make a sound on your first round, you can try each set of wires in turn until you hear the sound come from the ear piece.

If you prefer not to "experiment" looking for the speaker wires, you may disassemble the handset and check to see which two wires are connected to the earpiece. Many older phones feature a circular style ear and mouth piece on the handset that may simply be unscrewed. Some newer models may require you to pry the handset apart to gain access to the speaker.

Figure 4: Disassembled handset to find the speaker wire in the ear piece.

In any case, exercise caution not to break anything and make sure you can put it back together again. After you have identified which wires go to the earpiece in the handset, the next step is to modify the base.

Switch It Up

Once the speaker wires are located, we are going to wire in our MP3 player. We need an 1/8" stereo plug that ends in bare wires. If you have an old pair of ear buds or if your MP3 player came with a pair you are willing to sacrifice, simply cut the buds off the ends to create the cable we need. Carefully strip the wires from one side of the headphone cables (either the left or right speaker). Once you have stripped the wires, we are going to splice them into the handset speaker wires and our microswitch.

Figure 5: Wiring in the MP3 Player to the Phone.

In order to use the microswitch, we are going to find the "hook mechanism;" this is the piece that goes up and down when the handset is picked up. Depending on the type of phone you have chosen for this project, the next step might take some creativity. You will want to attach the microswitch to the moving piece of the hook mechanism so that when the phone is "on hook" (the handset is down), the connection to the speaker is open; when it's picked up ("off hook"), the connection is completed. I positioned my microswitch in such a way that the hook mechanism would push against it when the handset was down.

We want to wire one of the leads from our headset to the normally-closed position so that when the switch is released, the circuit is completed and the audio is allowed to play. Essentially, you will be breaking one side of the speaker connection with the microswitch.

You may need to remove most of the phone's internals to do this. That's okay, since we will want room inside to mount the MP3 player as well.

If you have followed these steps correctly, you should now be able to put a spooky MP3 of your choice onto the MP3 player and test out your work for the first part of this prop. Be sure to set your MP3 player to loop endlessly. Pick up the handset and make sure you can hear the player coming through the speaker.

If for any reason you cannot, be sure to check your wiring. These wires can often be very small and difficult to work with, so take your time and double-check your work. Be sure everything is working as it should, then reassemble the phone. If you picked a sufficiently small MP3 player, you should be able to hide it inside the phone itself. 

Figure 6: MP3 Player hidden in phone base.

There are plenty of great free spooky MP3 sounds you can download on the Internet, or you can make your own if you know how. Since we are using only one speaker, be sure to make your audio track of choice mono.

The second part of the prop allows the phone to ring when guests are near it and is much easier to make. To give the illusion of the phone's omnipresent sense for ringing, we are going to use an old-fashioned doorbell with a 2.5 inch bell and connect it to a wireless light outlet. The host can secretly hide the transmitter in their pocket or hand and control when the phone rings. These doorbells and the doorbell transformer can be found at most local hardware stores and online.

In order to hook the doorbell up to the wireless light outlet, we are going to use an old power cord for a PC and the doorbell transformer. The transformer will take the 120 VAC from the wireless light outlet and drop it down to a more usable 12-16 VAC for the doorbell itself.

Figure 7: The Doorbell Transformer hooked up to the Wireless Remote

Trim off the female end of the power cable and strip the wires back. Next, splice the end of the cable to the 120V side of the doorbell transformer and then wire the doorbell to the other side. Now, we can plug the cable into the outlet on the wireless transmitter, giving us a wireless ringer for the phone. You will need to turn the bell on and off by hand, so try to do so in a way that makes it sound like a phone ringing and not simply an endless ring.

Once the ringer is complete and tested, you can now hide it on the bottom of the table or desk that you are placing the phone on. Most tables and desks have a recessed area on the bottom which is perfect for hiding the mechanism. Practice a few times with the ringer to make sure you get the hang of making it sound like a phone, and be sure to stop once a guest picks up the handset! This prop is great because it has a nice startling effect of the loud bell ringing when people least expect it, and it's even creepier when guests realize they can answer the phone and hear the spooky voices from the other side.

This project was designed so that anyone could build it with simple-to-find parts, regardless of their skill level. A more advanced approach could be done using something such as an Arduino kit with an MP3 player board and PIR sensor to help automate the prop. You can find videos of the ghost phone in action at

For more fun Halloween project tips and ideas, be sure to check out my site at www.EerieAcresCemetery.comNV



Posted on 09/14 at 9:37 am
Posted in: Developing Perspectives

Don’t Get Stung by a Wall Wart

October 2014 Bryan Bergeron

Wall warts are used in place of internal AC-to-DC power supplies in most small devices — and for good reason. The powered unit can be more compact because of the obviously smaller parts count. There’s also no need to make allowances for convection cooling of components in the powered unit. The downside, of course, is the need to control a neverending, space-hungry herd of wall warts.

Until recently, a typical wall wart in my collection required at least two outlet spaces in my power strips: one for the prongs of the wall wart and at least one adjacent outlet partially obscured by the body of the wart. Given that new compact switching wall warts are so inexpensive, I recently upgraded my collection of conventional transformer and diode bridge warts to the switching variety. I’ve been happy with the upgrade — there’s more space in the outlets and less clutter around my workbench.

Unfortunately, I learned the hard way that the latest generation of “regulated output” switching wall warts can have at least one major shortcoming: the regulated output can be up to 100% over the stated output voltage with no load. For example, a 9 VDC wart can output up to 18 VDC with no load. This isn’t universal, but depends on the design of the switching supply.

I discovered this when I shipped out a dozen Arduino based animatronic systems for a research project. The systems left my shop — fully burned in — without a problem. However, the systems (which used 9 VDC switching wall warts for power) were DOA. I first thought of ESD, and modified the front end circuits of the animatronic systems to bleed off any electrostatic charges.

Luckily, before I sent the second batch of units off to the field, I ran across a thread in a forum about the no-load voltage levels in the same switching power supply warts I was using. It turned out that the users of my systems were plugging in the warts first, and then connecting the animatronic systems. This was guaranteed to generate a chipkilling spike if the no-load voltage was significantly greater than the load voltage. I solved the problem by ordering a dozen of the old-fashioned bulky wall warts with conventional non-switching circuitry. Problem solved — after quite a bit of expense repairing and reshipping the animatronic units.

Of course, not all switching wall warts suffer from this no-load voltage problem. The wall warts weren’t something I found on eBay. They were standard items from my favorite parts supplier. Bottom line: Verify that the wall wart’s output is what you expect before plugging it into that new system you’re designing. NV

Posted on 09/14 at 9:08 am
Posted in: Featured Article

Rubys Flame Extended Article

September 2014

A friend of ours, Ruby Joule, who is a dancer in the world famous Jigglewatts Burlesque Troupe from Austin, TX asked if we could help her with a prop she wanted for her stage act. She had been wanting to do something involving fire, but most venues tend to frown upon using real flames. She had seen photos of some of the Halloween props we had built, and asked us if we’d be interested in fabricating something for her.

She wanted us to create a four foot tall faux flame prop.  It needed to be easy to carry on and off stage by anyone immediately after her performance was completed. This was important as the stage has to be clear for the next act. This also meant it needed to stay cool all the time (no halogens) and be rugged as it would be subject to road life abuse and the occasional clumsy stagehand. We went through a few different designs, but eventually made the stage prop now known as "Ruby’s Flame."
We’ve had a lot of requests from others who have wanted to build this for their home haunts, and recently by a few drama teachers who wanted to use it in some school performances. One of them told us it was the hit of their play. Thanks for the inspiration, Ruby! 
Build the MDF Enclosure

Let’s get started by building the enclosure. Figure 1 shows the parts that will be necessary to complete this. Measurements to build the cabinet itself and the luan top with all the cut information are as follows:

2 — Long side panels cut to 23-1/2” L x 9-3/4” H
2 — Short panels cut to 7-1/8” W x 9-3/4” H
2 — Inside runners for suspending the luan top cut to 22 -1/8” L x 1” W, shelf for PC power supply cut to 6-3/4” W x 7-1/4” L, Luan top cut to 22-1/4” L x 7-1/8 “ W

NOTE: See the section on installing the legs and leg nuts before continuing — it’s a good idea to install the T-nuts that are needed to attach the legs before you assemble the enclosure!

Figure 1. The parts. Figure 2. The raw enclosure.
Figure 3. Side rails measured. Figure 4. Bottom shelf view. Figure 5. Bottom shelf with side rails installed.

Make the enclosure box by assembling the two long side panels and the two short panels to form a rectangle. The short panels fit inside the long side panels to form this box. Dimensions of the final box will be 23-1/2” L x 8-1/2” W x 9-3/4” H (Figure 2). Use wood glue and secure with wood screws.

Measure 1-1/2” down from the top, inside the enclosure, and attach a runner to each side. This is what will support the luan top panel. Use wood glue and secure with screws (Figure 3).

Figure 6. Top panel/full view
Figure 7. Half of top panel with measurements for the layout.

Turn the box over so its bottom is facing upright. Measure down 1” and over 3” from the side, then attach the shelf for the power supply so it sits about 1” from the bottom (Figures 4 and 5).

The Top Panel

This is the most important step to the whole project! The panel needs to fit snugly and be measured correctly as it will support the fans, the lighting, and the silk flame itself.

Measure to the center of the luan top and draw a line widthwise to divide the top (dividing line), then draw a second line lengthwise to divide the top again (center line). This will leave you with four sections to measure from. All of your measurements will start there, so make sure that everything is centered (Figure 6).

Each side will need to have one 5” hole and two 1-5/8” holes.

Figure 8. These marks show where to drill for the LEDs.

Figure 9. These marks show where to drill for the LEDs.

Figure 10. These marks show where to drill for the LEDs.

For the 5” hole, measure from the dividing line along the center line and make a mark at 3-3/4”. This will be the center of the 5” hole for each fan. Repeat this for the other side (Figure 7).

For the two 1-5/8” holes, measure 1- 3/8” from the edge of the top along the dividing line and make a mark. From this mark, you will measure 7-5/8” across the length of the luan top to mark the center of the 1-5/8” hole. The finished hole should be 1/2” from the length side and 2-5/8” from the width side. Repeat this for the remaining three holes. You will also need to drill out two holes for the 10 mm blue LEDs to mount into. We put one LED on each side of the center line and along the dividing line. You will want to drill a hole as in Figures 8, 9, and 10.

Helpful Tip: 
Take a scrap piece of luan and drill a hole approximately the same size as the 10 mm LED. You want the hole just big enough so the LED will fit snuggly without gluing it. This way, you will know what size drillbit to use to make the actual hole in the panel. We ended up using a step bit to get the exact size we needed, but I don’t recall what size it was. Using the scrap wood will allow you to figure out what the final hole size needs to be so you can be sure to drill the right size in the actual panel.

Building the Light Harnesses

We’ll begin with the light harnesses utilized. Start by taking about one foot of black wire and soldering it to one of the wires from a GU10 socket. It doesn’t matter which wire you use (Figure 11).

Figure 11. Solder the black wire to the GU10 socket. Figure 12. Solder the white wire to the GU10 socket. Figure 13. Shrink wrappng the wires.

Next, take about one foot of white wire and solder it to the other wire on the same GU10 socket and cover these solder joints with shrink wrap (Figures 12 and 13). You will now need to cut a second piece of black wire approximately one foot long. Solder the two black wires together with one of the wires from a second GU10 socket (Figure 14). Now, do the same thing with a piece of white wire. Cut a second piece approximately one foot long. Take the GU10 socket and solder these wires together with the remaining wire from the second GU10 socket (Figure 15). Shrink wrap both of these solder joints. This will complete the first of two wiring harnesses you will need to make for the GU10 LED lights. Figure 16 shows a shot of the completed wire harness.

Figure 14. Solder the second black wire to the second GU10 socket.  Figure 15. Solder the second white wire to the second GU10 socket. Figure 16. A completed lighting harness.

You will need two wiring harnesses, so repeat the steps above and set them aside for now.

Making the LED SpotLight Holders

To make the spotlight holders (Figure 17), you will need to use a step drill bit (Figure 18) and enlarge the hole in a shallow flange so the opening is the same size as the lens on the bulb (Figure 19). The easiest way we found to do this is to take a short piece of 1-1/2” PVC and place the flange on top; it will slip over the end of the pipe. Then, drill out the hole with the step bit. The lens on my LED spotlight is about 1-1/4”. If you have a drill press, it will make this easier, but it can be done with a handheld drill if you are careful (Figure 20).

Figure 17. LED spotlights in action. Figure 18. Step drill bit. Figure 19. The shallow flanges before and after expanding the size of the hole. 

Repeat this for all four of the necessary flanges, then set them aside for now. We ended up painting all of the parts black so they would disappear when the flame is on. This is a good time to paint parts if you choose to do so (Figure 21).

Figure 20. Enlarging the hole in the shallow flange with a step bit. Figure 21. We painted all the parts and hardware black.
Figure 22. Connecting the GU10 bulb to the GU10 socket.

The GU10 LED lightbulbs fit perfectly inside of 1-1/2” PVC/22-1/2 degree angled Els. They are also the perfect angle to shine onto the silk flame. The GU10 socket will come up from below the top panel of the enclosure, through the PVC EL. When the LED is attached, the bulb will sit perfectly inside the angled El (Figure 22). You can then cut a small disc of lighting gel and place it on the bulb to take intense heat away. However, these LEDs barely get warm. Next, take the coupling flange you drilled out earlier and snap it onto the flange to secure the gel and bulb in place (Figure 23).

Figure 23. Attaching the shallow flange to the PVC light holders. Figure 24. Drilling the fan holes with a 5" hole saw. Figure 25. We used 1/2" Tek lath screws to attach each fan to the bottom of the top panel.  Figure 26. Laying a bead of clear silicone caulking around the base of each fan.

Installing the Fans

The flange itself will lock onto the PVC El, so no glue or fasteners are needed. Besides, you might want to alter the color of the flame at some point. We will eventually position the Els and then glue the base to the top panel of the enclosure, but we’ll do that later once the silk that creates the flames is actually flying. The assembly of the spotlights will be part of the final assembly and wiring.

The particular fans we use are very dangerous when spinning and could probably take off a finger, so always use extreme caution!

The fan’s casing is square and the holes we drilled are round, so we used all-purpose silicone caulking to help plug up around the fans and also to assist holding them securely to the top panel. We’ll use four 1/2” lath screws per fan to secure them, as well.

Figure 27. Both fans mounted to the top panel of our enclosure with screws and clear silicone caulking.  Figure 28. Flipping over the top panel so we could smooth out the caulking.

Start by drilling some very small holes into the luan in each corner, lining up with the holes in the corner of the fan (Figure 24). You will need to position the fan so that you can put a screw into each corner to secure it to the top panel (Figure 25). Make sure each corner lines up with the holes in the corner of the fan so you can put a screw into each hole to secure it. You will also want to make sure that the fans are facing the correct direction so when they spin, the air flow will be blowing where it’s supposed to. Usually, the label side is what you want to see when it is mounted to the top and flipped back over to the operating position.

Figure 29. Smoothing out the caulking using some rubbing alcohol. Figure 30. Wiring up the 10mm blue LEDs.
Figure 31. We drilled a small hole in the base of the power supply to attach it to the shelf.

Make sure to fill in any open spaces around the hole so you don’t lose any air flow (Figures 26 and 27). You can run a thick bead of the silicone caulking around the fan to help seal it. Once this is done, flip the panel over and smooth out the silicone (Figures 28 and 29). Set the piece aside to dry overnight.

Helpful Hint:
Greg showed me a little trick he learned from a tile installer. To smooth out the silicone caulking, put on a nitrate glove and dip a finger into some rubbing alcohol. Then, run your finger over the silicone. The silicone won’t stick to the glove due to the rubbing alcohol.


Continue to Rubys Flame Extended Online Version - Part 2  ..

Posted on 09/14 at 10:31 am
Posted in: Nuts and Volts

What’s in the box?!

September 2014

Monster in a Box! Just one of the many Halloween projects found in the September 2014 Halloween Spectacular issue of Nuts & Volts. Just imagine that there is a Fire breathing monster inside trying to escape! Activated by motion sensors, all you'll need to do is get the unexpect tricker treaters near the box for it to start shaking with the fog machine and mp3 player inside, you'll be sure to get a nice scare out of the kids this year. Read more to watch a video of the Monster in a Box! 

Posted on 08/14 at 11:17 am
Posted in: Featured Article

The Inner Workings of Rock Golem

September 2014 Shannon Chappell

Ever since I was a kid, I’ve been taking things apart and putting them back together; sometimes right, sometimes wrong, blowing fuses, and generally being intensely curious. I would always brag that there was nothing I owned which I didn't take apart to see how it worked. I never had much help or support, so I started teaching myself, finding unique ways to overcome problems for my builds through the years. About a year ago, I decided it was time to crawl out from under my rock and show the world what I was making ...

Ever since I was a kid, I’ve been taking things apart and putting them back together; sometimes right, sometimes wrong, blowing fuses, and generally being intensely curious. I would always brag that there was nothing I owned which I didn't take apart to see how it worked. I never had much help or support, so I started teaching myself, finding unique ways to overcome problems for my builds through the years. About a year ago, I decided it was time to crawl out from under my rock and show the world what I was making ...

So, without further adieu, I introduce my Steampunk-inspired Rock Golem from the depths of middle Earth (a.k.a., my basement work room). This colossus measures in at 12 feet tall and weighs around 300 pounds. He is primarily built out of mattress foam over a PVC pipe skeleton.

My Golem has an impressive list of features:

• Articulated head with servo-actuated/smoke-spewing jaws, and Larson Scanner eyes.
• Right limb hand manipulator.
• Left limb dynamically-controlled spinning energy weapon.
• A working intricate chest cavity geartrain.
• Several hundred LEDs split among several lighting effect systems.
• Fully autonomous; powered by a 12V8Ahr SLA battery in each foot.
• Wearable as a fully walking costume. An operator enters via the back panel, locks into ski boot stilts, and assumes (almost) full control of this 100% self-sufficient costume.

Skeleton of the Golem. The back hatch where the operator gets inside.


Underlying Technology: Power management and switching circuits, multicolor LED lighting, microcontrollers for sequencing and complex effect synchronization, sound effect triggering, and radio signal remote control via gesture and motion detection.

Alternate Uses: The power management circuits and LED lighting systems could be useful in solar power systems, offgrid power areas, and educational green energy models. Using microcontrollers to sequence or create complex reactions to input states can be useful in building alarm systems, monitoring water levels, or creating lighting macros for stage use. Radio control and motion sense systems such as the one used here could be adapted to detect a medical state (e .g., horizontal orientation could mean the wearer was incapacitated and the radio system could alert a central station about this.

What did we miss? Do you have other ideas we may not have thought of? We are interested in how the technology showcased in articles may otherwise be applied. If you have ideas or comments, please send them to

FIGURE A. The Sorceress (Kayna Hardman) with her crystal chest and arm bracelet, wirelessly controlling the Golem.

Behind All Great Men

Rock Golem comes with its very own Sorceress (Figure A). One of the myths of the Golem is that it is brought to life by a magical person. In this instance, the Sorceress molded the Golem from the Earth and detritus around her, including rocks, machine parts, glass, and wood. This Sorceress also directly controls parts of the Golem via gesture command, activating Golem’s chest gears by pressing her own chest piece. She’s also in charge of his armament, controlling the spinning crystal energy weapon by raising her own arm and making a spinning motion with her fingers.

“Why did you make this?” is the most common question I get. I had seen big costumes at events before, but I thought I could go bigger. I built it particularly for the 2013 Calgary Entertainment Exposition, but due to its size, I was denied permission to have it walk through the event. It sat in a storage room growing spider webs until I was approached by Shannon Hoover from the Calgary Mini Maker Faire, who brought us out to the light of day. Ever since, we’ve been delighting large costume fans.


Sketches, Designs, and the Unknown

FIGURE 1. A very early stage in the process of making the skeleton.

I’d like to say I have 3D models with accurate measurements and blueprints, but I just kind of do things on the fly. So, in the instance of my Golem, I knew what I wanted as far as the height and rock-like appearance. Other than that, I made it up as I went along. The first step was to take a physical outline of the person who would be piloting it (not me) by having them stand on buckets against a wall. Tracing this general shape onto on old bed sheet gave me an initial height of approximately 10’6”, so I started building a skeleton to this size (Figure 1). As with any adolescent, my Golem grew a bit during his youth, adding another 18 inches to make an adult size of 12’ tall. I would do some general drawings, mainly so I wouldn’t forget ideas I came up with the night before.

What it Takes to Make a Golem

Lots and lots of stubbornness! You will need this as you spend weeks on end, up to the wee hours cutting up mattress after mattress into rocks, shaping them, painting them, and decorating them (Figure 2). Leaving the artistic stuff aside, just learning the electronics to make him come alive was quite a task for me. I am a novice when it comes to electronics, but I do have a very strong desire to learn. Most of what I know comes from years of taking things apart, hacking kid’s toys, owning a copy of Forrest Mims’ Getting Started in Electronics, and plenty of trial and error.

So, this is basically my story of how I hacked the Golem’s electronics to life. Although I got it working with tenacity and determination, I knew I wanted to make it better and more reliable. So, I got some help from Solarbotics Ltd., who is also here in Calgary with us.

To make Rock Golem what I envisioned, I needed a gameplan. I sat down with Solarbotics, and we documented all the systems I had put together — including power systems and labelling all the wiring (see Figure 3) — and what my wish list was for improvements. After prioritizing these upgrades (we were on a tight time schedule), Solarbotics’ president, Dave Hrynkiw pinned down the new control structure and what the features were (Figure 4). Although my hacked electronics worked, they were twitchy and untunable. We decided on splitting the 15 lighting effects between two of Solarbotics’ Ardweeny/Double Rainbow controllers and three SparkFun Pro Minis.

FIGURE 2. Cutting the foam rocks and fitting them together. FIGURE 3. Breaking down the electrical systems for Solarbotics. FIGURE 4. Figuring out what systems to tie together, what voltages to make common, and what subsystems were a priority.


What it Takes to Make a Golem Walk

The best place to start is at the very foundation: the skeleton. Engineering a 12 foot, 300 pound costume to walk with no mechanical aid was a “feat” to say the least Figure 5). (I’m proud to report that the Golem never fell once.) For the frame, I had to come up with something strong, yet light and malleable. Being that my background is in building maintenance, I decided PVC pex pipe would be the best to use.

This led to many days of bending, shaping, gluing, and screwing together pieces of pipe until I had the full skeleton of the Golem created (see Figure 6).The full extent of work that went into the engineering of the skeleton was quite long, but what I did was to study how the human skeleton works and transfer the concepts to the Golem (Figure 7). This was actually harder than I thought it would be due to the size and the fact that someone less than half its height had to walk Rock Golem around.

After trying to use assisted walking devices such as hydraulics on the legs (which only made him lose balance), we came up with a technique where the operator was able to successfully walk the Golem around while turning his head and moving his arm and hand.

The biggest obstacle in the build process of the skeleton was attaching the energy crystal weapon which was much heavier than the rest of the costume. For this, I created strengthened joints all up the arm and upper chest to distribute the weight evenly over the upper body. This left him very front heavy though, so I designed a ratchet system spinal cord that connected his upper shoulders to one of his feet creating a core of balance, then used the Golem’s own weight to balance him.


FIGURE 5. Walking down the hallway. The walls helped keep the Golem from falling. FIGURE 6. The Golem skeleton from behind. FIGURE 7. The operator in the foot stilts, taking baby Golem steps at first.


LEDs — It’s an Abusive Relationship

I learned my first hard lesson on the use of current-limiting resistors. Initially, I ran two wires to every LED and many more back to a single resistor. This created a rat’s nest of wiring and LED grids that were power hogs that created substantial heat in the few current-limiting resistors.

Torso LEDs

FIGURE 8. Lighting tests on the leg to see what the best way to utilize the LED strips was.

There is well over 50 linear feet of red LED strips mounted among the Golem’s internals. Each strip is cut into four-LED sections, then re-wired back together to create a single glowing effect in the cracks between the rocks. It was a very long process, but well worth the effort (Figure 8). The LED strips originally ran back to a standard 44-option controller (the white ones that come with most LED strips) which allowed me to create a very nice pulsing lava effect. This same method controlled the tubes on the chest, but at a slightly different frequency. All the protruding crystals have an amber LED under them.

Rock Golem’s upper back housed a small tube-shaped power cell hacked from a dollar store toy (dollar stores are where I get most of my hackable electronics). I also added wire mesh grids to give more depth and mechanical integration to the rocks. Under each grid were plastic red emergency exit signs, backlighted with flickering LEDs from electronic tea candles.

The glowing letters on the collar were created by carving them in the foam, filling them with hot glue, then embedding approximately 50 LEDs. This was the first place that I appreciated the benefit of series-wired LEDs rather than parallel ones.

The Crystal Energy Weapon

This is the centerpiece of the Golem (see Figures 9 and 10). It is designed to spin the outer three blades around a central “power core.” The weapon’s power core light show consists of a column of 14 rings of eight LEDs each, surrounded by an array of individual LEDs illuminating the edge crystals. We split the 14 rings into two sets of seven pairs, with output 1 driving rings one and eight; output 2 driving rings two and nine, etc. Each ring was powered by its own N0106 FET, so each output drove two FET gates.

The original plan was to show the weapon “charging” via the rings pulsing sequentially in increasing frequency, but until that animation was ready, I set it for a steady “on” which was a bad idea — 112 low-efficiency orange LEDs draw substantial power. An input was connected to an RC1 output to receive an “Animation Start” command, causing the ring sequencing to increase from a slow single-ring climbing pulse, to a more rapid one involving increasingly more simultaneously-on rings.

FIGURE 9. The Golem's energy crystal weapon. The three outside blades rotate faster and faster, creating a pulsing charge in the center crystals getting it ready to fire. FIGURE 10. Power lines that feed the crystals and the gear system which spins the outer blades.

FIGURE 11. The interior of the weapon arm, with the drill mounted and made accessible to the operator.

Don’t try to run four amps through a single strand of telephone wire! It glows and melts every wire in the bundle next to it! For that matter, avoid using telephone wire in any circuit where there is a chance it will flex — this stuff is brittle.

The mechanics behind the spinning outer blades were based on the bearing system from a ceiling fan. The effect I hoped to achieve was that as they spun faster, they would create an electrical charge that would seem to power the crystals. I used a 12 VDC drill mounted to a hand-cut wooden 3:1 gear reduction system that was attached to the ceiling fan assembly. The drill’s gearmotor assembly was cut from the handle/trigger portion, and motor wires were extended.

With the trigger easily hand-reachable, the pilot could slowly pull the trigger and have the blades ramp up to full speed (see Figure 11). This was effective and worked quite well, but the drill gearmotor was overloaded and pulled lots of power, rapidly killing the batteries. This was corrected later with the help of Solarbotics when we replaced the drill with a much higher geared unit.

Figure12. the sorceress’ costume pressing the center button of the chest crystals activates the golem's chest gears; lifting the crystal bracelet activates the spinning weapon blade.

The Sorceress

The Sorceress’ initial role was to hand-guide the Golem since pilot visibility was very low. As I explored the idea of the Sorceress, we wanted her to be in more control of the Golem. So, I built her a whole new costume featuring remote control functions. The original design used a highly decorated LED closet light dome connected to an IR transmitter circuit hidden in the back of the dress. The IR LED was tucked in among the crystals of her center chestpiece, with the wire woven back to the rear electronics (see Figure 12). The dome chestpiece was retrofitted with harvested limit switches from a VCR, so a push to the chestpiece would signal the Golem pilot it was time to move.

IR communication seemed like a good idea, but the receiver circuit in the Golem had a hard time actually getting the signal in a dense electrically-noisy environment. It worked sporadically at best — often self-activating — so it was back to the drawing board.

Communication ended up being a straightforward 433 kHz four-channel key fob setup. We were always in close range (less than 3M/10’) for strong signal communication, and it left two spare channels for other potential “enchantments.” We wanted to use a Synapse wireless RF100 2.4 GHz radio for a “bulletproof” signal, but time constraints led to this solution which seems adequate for now. Lesson learned with radios: Always check your transmitter batteries first before doing any other debugging!

The Sorceress’ collar is an important accent to her costume, featuring an ATtiny45-based “FireFly” LED board powered by a small 7.4V Lipoly cell (regulated down to 5V), running the fabulous “flickering candle” code by Park Hays. It drives 34 LEDs through a single FET to create a very convincing flame flicker.

Figure 13. Interior of the head, getting the lighting all in place Figure 14. Shaping the face out of some scraps of sheet metal i had laying around. Figure 15. The electronics of the face, and the pulley system that activates the jaw.

The Head of the Golem

I wasn’t sure on how to approach the head. I had built one out of rock, but found it was not suited to the rest of the Golem, so I decided to go the route of a machine-like face merged into the rock (Figures 13 and 14). For lighting, the head had some pulsating cracks which were tied into the body circuits. Some LED circuits made the mouth glow orange and the cylon-style eye glow yellow, but I wanted more life in the face, so I added a Larsen scanner. I had a chaser beacon that came out of the lights that are stuck on the roofs of utility vehicles. I hacked this by tracing the circuits and adding on longer wires so I could put all the LEDs in a row. I also had to change out the resistors on the board to suit the LEDs I was using (Figures 15 and 16).

Figure 16. The hacked chaser beacon.

Now all that was left to do was to figure out how to get the LEDs to create a line of light across the middle of the eye instead of the round bursts of light. For this, I took a acrylic rod and placed all the LEDs behind it. The result was the LED light was refracted out the other side as a flat beam of light. When they went off in sequence, I had a scanner. I wasn’t quite done because I also wanted to have the jaw open and close. Try as we might to run a servo off the Double-Rainbow 2 controller, all the PWM channels were busy, and we couldn’t trick it into easily bit-banging a servo drive signal without causing issues elsewhere. So, we grabbed another Pro Mini just to run the jaw animations.

At the time, I was not really familiar on how servos worked, so I came up with a very rudimentary system of pulleys, lamp parts, string, and eye loops with which I was able to control the jaw via the operator’s head. This was done by creating a spring-activated rod with a salad bowl that came down from the head of the Golem. When the operator pus his head in the bowl and pushes up and down, the jaw would open and close (this was later changed to a servo; refer to Figure 17). The head was mounted on a lazy Susan, so when the operator put his head in the bowl he could also turn the Golem’s head side to side. I decided to put in some smoke effects as well, and by luck I came across a device called the Dragon Puffer which was used to detect drafts in houses by releasing smoke. I drilled a hole in the bottom of the lazy Susan, mounted a hose, and attached the Dragon Puffer at the other end so the Golem “breathed” smoke. The only problem with this was that the smoke could not make it up the tube. So, I took apart a video card heatsink, removed the fan, and tied it into the tube, then connected a 9V battery with a temporary switch.

The Hand

There were not a lot of electronics here, but I created a large articulating hand using aircraft cable, PVC tubing, a cut-up tape measure, and latex tubing to create the movement of the fingers (see Figures 18 and 19). Since they were too large to be controlled individually, I had one lever that the operator would grasp and squeeze to open and close them all at once. This way, he could come up behind people, put his hand over their head and pretend to crush them.

Figure 17. Finished head with bowl attachment. Figure 18. The workings of the Golem's hand. Figure 19. Pulling the bar would make the hand open and close.


The Center Gear Chest Piece

Figure 20. The chest gears.
Figure 21. The back of the chest gears, and all the system emergency shutdown switches (before the Solarbotics upgrade).

Through the years, I have been taking apart hundreds of printers and saving all the gears. So, I painted a bunch of them in a brass color, aged them up, and mounted them on a piece of plexi (see Figure 20). To drive all the gears, I used a 12V motor I got from a local electronics surplus store and a vacuum cleaner belt. To light it up, I wanted hot spots of light behind the gears. I used chicken wire mesh as a grid and attached 50+ LEDs behind the plexi to give a warm uneven light.

Figure 22. Everyone was just as amazed with the inside as with the outside!

In the center of the gears is a central core power cell which also lights up and pulses. To achieve this pulse, I hacked another chaser beacon and placed it behind a glass jar filled with orange scented oil beads. As each LED  goes through its programmed rotation, it reflects off all the beads making very interesting patterns (Figure 21).

The Cockpit

Everything converges in the “cockpit” of the body. Having very little exposure to the “maker” world, I thought it was best to hide the electronics and the workings of the Golem. I couldn’t have been more wrong (Figure 22). It turned out everyone — no matter what their interests in electronics were — wanted to see how it worked. The insanity of the inside with flashing lights, hundreds of feet of wire, and the fact that someone got in there was very fascinating.

During the wiring process, I learned to mount things so they were accessible, label things properly (which Solarbotics greatly appreciated), put proper connectors on, have a proper soldering technique, and so on. I also put in around 25 pole and temporary switches to be able to shut down different systems in case of shorts or to conserve power. There was also a system of fans to help with the heat of the costume. Amazingly, the Golem never had a problem because everything worked as it should.

Golem 2.0

Solarbotics “sponsored” the upgrade for all of the electronics and continues to work with me as I improve my Golem. As mentioned, I come from an industrial background where black is the live wire and white is neutral. Solarbotics comes from a low voltage background where red is live and black is ground. Let’s just say that we discovered how robust Atmel makes their microcontrollers against reverse voltage damage that melts wires together.

The Double Rainbow controllers were originally designed as Arduino-compatible/six-channel high current drivers for powering two independent RGB LED strips (R/G/B * 2), plus offered a bunch of Ground/Voltage/Signal (GVS) pins for wiring up controls. They proved to be almost perfect for the job, with handy three-wire I/O connections and screw-down terminals. Most features were wired through the cockpit control panel with beefy toggle switches, so the pilot could toggle effects for best battery life or debugging purposes.

To sum this all up, at the end of the day what it takes to build one of these guys is a good inventory of discarded treasures, an understanding partner, and sheer stubborn determination to finish no matter what. Or, more simply stated as Thomas Edison once said, “To invent, you need a good imagination and a pile of junk.”  NV

Posted on 08/14 at 9:29 am
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